UNION, Conn. -- It's time to add gassy trees to the list of climate concerns.
According to a new study by Yale University's School of Forestry and Environmental Studies, diseased trees may be releasing unusually large amounts of methane gas into the air. If the data holds up, it could alter forest management strategies around the world and change the calculations for how much trees are able to offset carbon emissions.
"If we're using forests as a climate mitigation tool, we have to know what we're getting," said Kristofer Covey, a Ph.D candidate who worked on the study. "Carbon offsets could be changed somewhat by this."
To be sure, the new findings don't negate the beneficial aspects of trees, which absorb carbon dioxide and produce oxygen. But it may give foresters some pause in thinking about what mix of age and species of trees is ideal for the environment.
"There's methane sneaking out the back door," Covey said, ushering visitors along a hiking trail at the 7,800-acre Yale-Myers Forest in northeastern Connecticut. "This is a very preliminary study, but there's a potential for this to be widespread. What we'd like to do is put together a global assessment, looking at a bunch of questions."
As with many scientific endeavors, the methane discovery happened by accident. Robert Warren, a former postdoctoral researcher at Yale, was showing some students at the forest how to take tree core samples. Suddenly, one of the trees began to spit out gas.
One of Warren's students decided to see if the gas was flammable by lighting it, and a moment later, "there was this flame coming out of the tree," said Mark Bradford, an assistant professor of terrestrial ecosystem ecology at Yale. "Robert called me up and asked what the heck was going on."
It prompted Yale researchers to study 60 trees at the forest, including common trees such as red maples, red oaks, hemlocks, pines and birches. Some of the trees were located in an upland area of the forest and others came from a wetland area.
Scientists drilled into the trees, plugged the holes with rubber stoppers and used special syringes to extract gas samples. The samples went back to New Haven for analysis.
What scientists found was startling: methane concentrations in some cases that were 80,000 times the normal level. Red maples had the highest methane emissions. Also, the rate of emission tripled in the summer when temperatures were warmest.
Other big factors were disease and age. The trees that produced methane were between 80 and 100 years old, and had a common fungal disease known as heart rot.
Assuming the methane levels in the Yale study are consistent elsewhere, they would reduce a forest's overall carbon sequestration benefit by 18 percent. ("Sequestration" is simply the intake and storage of the element carbon.)
"This doesn't tell us yet about what's going on in other places," Covey said. "People don't realize that trees and forests are increasingly dynamic."
Call Jim Shelton at 203-789-5664. To receive breaking news first - text the word nhnews to 22700. *Msg & Data Rates May Apply. Text HELP for help. Text STOP to cancel.